This invention relates to the synthesis of hydrocarbyl-bridged indenes.
Hydrocarbyl Bridged Indenexe2x80x94means collectively all isomers of a compound of Formula I: 
wherein xe2x80x9cRxe2x80x9d is a hydrocarbyl group.
1,2-bis(indenyl)ethane or EBIxe2x80x94means collectively all isomers of Formula II: 
in which the symbol xe2x80x3(xe2x80x3 indicates a 1,2-bis(indenyl-1)ethane which has a 1,2, 1,2xe2x80x2 double bond (thermodynamic EBI, BRN No. 3055002, CAS RN No. 18657-57-3) or a 2,3 2xe2x80x2,3xe2x80x2 double bond (kinetic EBI, BRN No. 3083835, CAS RN Nos. 15721-07-0, 18686-04-9, 18686-05-0). atoms are asymmetric when substituted.
Each of the ring substituents may be hydrogen or any one to ten carbon atom hydrocarbyl group. Each ring substituent may be the same as or different from any other ring substituent. One to ten carbon atom alkyl groups are preferred. 2,2xe2x80x2 methyl and 4,7, 4xe2x80x27xe2x80x2 dimethyl EBIs are representative.
Meso and rac (racemic) forms of kinetic EBI and thermal isomerization of kinetic to thermodynamic EBI are known phenomena. Marxc3xa9chal, et al, Bulletin de la Societe Chimique de France (1967) 8:2954-2961.
Kinetic and thermodynamic EBI are interchangeably useful separately and in mixtures as ligands for metallocene olefin polymerization catalysts. However, the large-scale production of kinetic EBI is constrained because the thermodynamic isomer is produced at temperatures below about xe2x88x9270xc2x0 C.; whereas, at higher temperatures low yields of kinetic EBI consequent from Spiro indene and vinylindene impurities may result. See, e.g., Yang, et al., SYNLETT (1996) 147 and Collins, et al., J. Organometallic Chem. (1988) 342:21 (thermodynamic EBI synthesized at xe2x88x9278xc2x0 C. stirred overnight and warmed to room temperature). See also Ewen, J., et al., J.Am.Chem.Soc. (1987) 109:6544-6545 and Grossman, R., et al., Organometallics (1991) 10:1501-1505 (50% to 80% recrystallized yields of thermodynamic isomer because of the formation of spiroindene by-product).
This invention provides a method for the synthesis of 1,2-bis(indenyl) hydrocarbyl compounds, typically 1,2-bis(indenyl) alkanes. Pursuant to one aspect of the invention, an indenyl lithenide is treated with a terminal dihaloalkane and tetrahydrofuran (THF) wherein a reaction mixture containing a hydrocarbyl bridged indene is produced. The reaction is illustrated by Equation 1: 
Equation 1
In general, the synthesis of hydrocarbyl bridged indenes pursuant to this invention may be accomplished by treating an indenyl alkali metalide compounds of formula XZX, in which Z is any hydrocarbyl and X is any halogen, e.g., chlorine, preferably in a non-interfering medium, preferably diethyl ether and THF. Preferably, Z is xe2x80x94(CH2)nxe2x80x94; n=1-20.
The indenyl alkali metalide is prepared treating indene with an alkali metal alkyl in an ether medium at a temperature of xe2x88x9210 to xe2x88x9220xc2x0 C. Alkali metal alkyls useful in this invention have the formula MOR, wherein M is any alkali metal and R is an alkyl group, typically a C1 to C10 alkyl group. N-butyllithium is preferred.
The alkali metalide synthesis reaction mixture typically comprises the selected alkali metal alkyl and the ether medium in which it is produced. Hydrocarbyl bridged indenes may be produced by combining a selected terminal dibromoalkane and THF with an appropriate metalide synthesis reaction mixture. Alternatively, the alkali metalide may first be isolated from the reaction mixture in which it is synthesized. According to one embodiment of the invention, the isolated indenide alkali metalide and THF are then reacted with a dibromoalkane, typically at room temperature, wherein a reaction mixture containing a hydrocarbyl bridged indene is produced. No reaction occurs upon combination of the dibromoalkane with the alkali metalide reaction mixture in ethyl ether.